For a long, long time, suiting up creatures with an enchantment was considered to be a poor strategic choice, at least from a Limited perspective. Sure, you may have just given your dragon or goblin or elf or brushwagg some sweet new stats, but you had also just stapled a giant, flashing bullseye to the poor creature’s forehead. Any removal spell that could kill your monster would also now net a free card, and your opponent would be up in resources at least, while most likely gaining tempo and board control as well. Very few auras were worth this risk, and even those that that bestowed exceptionally powerful boosts were often left in sideboards.